Recently exposed stone faces, for example in quarry faces, road and rail cuttings, scree slopes, concrete structures and new building stone, can cause visual pollution given their stark contrast with more mature “weathered” surroundings. The problem of the visual impact of newly exposed stone has been recognized by several authorities, including the Department of the Environment, U.K., which has funded research into quarry restoration, and by the Design Council, U.K. and English Heritage, U.K. which has researched the problem on buildings.
In the past, the only solution to the problem of visual pollution was to allow time for the slow natural colonization of the surfaces by microorganisms, which brought about a color change to the stone, alleviating the negative visual impact. Expediting this provcess has at times been attempted on a small scale, by the addition in-situ to structure repairs of substances such as soot and manure. Some such methods are described in “Lichens on Man-Made Surfaces; Encouragement and Removal,” F. Dobson, British Lichen Society, 1996. In quarries, the visual impact of the newly exposed faces has sometimes been addressed by burying the faces with scree. This method is described in “Landform Replication as a Technique for the Restoration of Limestone Quarries,” J. Gunn et. al., 1992. H.M.S.O. In conjunction with this latter method, hydraulic seeding, which is a method of spraying grass seeds in a nutritive medium over near horizontal soil surfaces is sometimes used.
On a laboratory scale, micro organic communities are sometimes encouraged to grow on stone so that their impact on the stone surface can be studied for biological research purposes. Nutritive media are used to encourage this growth. Some of these media are given in “Handbook of Media for Environmental Microbiology”, R. M. Atlas, 1995. However, these microorganisms are only grown on the stone surface for a relatively short period of time, and not long enough in order to effectuate a visual stone change and produce an aesthetically pleasing appearance to outdoor, weathered stone.
Allowing only natural-time colonization of the stone surfaces is extremely slow, and burying methods on a large scale are expensive. What is needed in the art is a method of speeding up the colonization of the newly exposed stone surfaces by the natural pioneering micro-organic community, using the acquisition of suitable pioneering communities and their application to the stone faces by a method which accelerates their colonization.